1. Field of the Invention
The present invention relates to a system and method of measuring the distance and determining the relative position of a transceiver or plurality of transceivers to a set of transceivers with known locations using a radio frequency network. More specifically, the present invention relates to a system and that utilizes a master anchor transceiver and a plurality of slave anchor transceivers to determine the relative coordinates of a target transceiver. The method of the present invention involves the transmission of a time-of-flight (TOF) initialization signal by the master anchor transceiver, generation of a TOF response transmission by the target transceiver, calculation of the distances between the target transceiver and each anchor transceiver, transmission of a TOF distance report by the master anchor transceiver. Frequencies utilized are in what is considered the ultra-wideband spectrum, eg. 3.1 gHz-10.6 gHz. Travel times can be measured. Using relevant mathematical calculations, a distance measurement can be resolved between each target and each anchor which can be used to calculate a relative position.
2. Description of Prior Art
It is known in the prior art to use a plurality of anchor transceivers positioned in fixed locations to determine the location of a target transceiver that is located within the perimeter of those anchors. For example, in a warehouse setting, anchor transceivers can be placed at various locations, including the four corners of the building, such that the anchors are capable of generating and receiving RF signals from a target transceiver located within the building, and thus, within the perimeter of the area defined by the anchors. Because the location of the anchors is previously known, the location of a target transceiver can be quickly and easily determined by measuring the TOF of an RF signal between the target transceiver and two or more of the anchor transceivers. From the TOF data, the distance from the target transceiver to each anchor transceiver can be calculated. Because the distances between each of the anchor transceivers is known, simple geometry calculations may be utilized to determine the coordinates of the target transceiver relative to the anchor transceivers.
While these simple methods work well to determine the position of a target transceiver “inside the box”, they do not work well for determining the position of a target transceiver that is “outside the box” as errors are significantly magnified. Thus, what is needed is a system for accurately determining the location of a target transceiver that is outside the perimeter defined by anchor transceivers, commonly referred to as outside the box.